level indicator presentation

7/31/2019 Level Indicator Presentation

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Bunggo, Desirie Joy T.Dela Cruz, Jill M.Emalada, John Christopher P.Ngo, Jemelyn C.

Ramos, Aileen M.


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Level Indicator also known as level gauge orlevel sensor.

A common variable in the industrial process.A device used to determine the amount of gas, liquid, or solid inside a vessel.The type used is usually dependent on themedium measured.Selection of device is dependent on theapplication and the industrial process.


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How often the level is measuredEvery hour, daily, continuously

Type of medium measuredGas, liquid, solidCorrosive

The vessel or location to which the medium isstored (dam, open sea, tank)


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Direct MethodMeasurement is based on the physical surface of

the medium with respect to a reference point.

Indirect MethodLevel is determined by measuring other qualitiesof the medium such as weight and static pressure.


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DIRECT METHOD

Float

RadarLaserSight GlassDip StickDisplacement

INDIRECT METHOD

Electrical capacitance

Differential head/pressureReflex level gauge,Transparent level gauge, BiColor level gauge


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consist of a metal bar on which a scale isetched. The bar is fixed at a known position in

the liquid-containing vessel. A levelmeasurement is made by removing theinstrument from the vessel and reading off how far up the scale the liquid has wetted.


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the position of the float on the surface liquidis measured by means of a suitable

transducer.


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The technique involves directing a constant-amplitude, frequency-modulated microwave

signal at the liquid surface. A receivermeasures the phase difference between thereflected signal and the original signaltransmitted directly through air.


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The laser unit is installed above the deck,isolated from the tank by a sight glass and

targeting the liquid level surface with a lowpower laser beam.


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Is a tubular glass or transparent plastic tubethat reflects the liquid level inside the vessel.

Located outside and is parallel to the vessel.


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consists of two concentric tubes made of aluminium or stainless steel, depending on

the construction of the tank. The inner tube issupported by the outer tube by means of concentric insulators placed at regularlyspaced intervals along the whole length of the tubes. The resulting assembly forms aseries of cylindrical capacitors, having thesame total height as the tank.


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1. Outer tube2. Inner tube3. Concentric electrical insulator4. Isolationof inner tube

sections by a gap or dielectricplug

5. Isolation from the tankbottom6. Connections between the

sections of the outer tube tomake a single electricalconductor.

7.Data signal connections fromthe gauge to the junction boxoutside the cargo tank

8. LNG cargo tank


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The difference in pressures between to pointsin a vessel depends on the fluids between

these two points. Usually, a seal liquid is usedin the two connecting pipes (legs) to preventplugging at the sensing points.


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By Archimedes principle, a body immersed ina liquid is buoyed by a force equal to the

weight of the liquid displaced by thebody. Thus, a body that is more dense thanthe liquid can be placed in the vessel, and theamount of liquid displaced by the body,measured by the weight of the body when inthe liquid, can be used to determine thelevel.


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Indicator Advantages Disadvantages Application


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Indicator Advantages Disadvantages Application

Float Can be used for switches cannot be used withsticky fluids whichcoat the float

fuel storage tanks, water tanks, other pressure less storagetanks and lubricating oil storagetanks

Displacement good accuracy limited range cost of externalmounting for highpressures

Level, contents orinterface measurement Condensate drums Separators Flash vessels Storage vessels HP and LP heaters

DifferentialPressure

good accuracy large range

applicable to slurrieswith use of sealed lines

assumes constantdensity

sealed linessensitive totemperature

pressure vessels, tanks Boilers

ElectricalCapacitance

applicable for slurries level switch for manydifficult fluids

affected by densityvariations

silos, bins tanks,


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level indicator presentation

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